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FishbeginnerFreshwater

Molly

Poecilia sphenops

AnimaliaChordataActinopterygiiPoeciliidae

📍 Central America & Mexico

Ask Finn

Mollies are versatile livebearers available in many colour forms including black, dalmatian, and balloon. They are adaptable to a wide range of conditions including brackish water. Females give birth to live young and breed prolifically in captivity.

Size3"
Min Tank15g
School3+
peaceful
Zonemid

Care Guide

Diet

Mollies are omnivores and should be fed a varied diet of high-quality flake food, spirulina-based pellets, and regular supplements of blanched vegetables like zucchini and spinach. Offer frozen or live brine shrimp 2-3 times weekly as protein. Feed small amounts once daily, only what they can consume in 2-3 minutes.

Behavior

Mollies are peaceful, active swimmers that spend most of their time in mid-water zones grazing and exploring. Males may display territorial or harassing behavior toward females, particularly during breeding season, so maintain a 2:1 or 3:1 female-to-male ratio. They are social fish and do best in groups of at least 3, preferring the company of their own kind.

Breeding

Mollies breed prolifically in captivity with minimal intervention—females are livebearers that produce 20-100 fry every 4-6 weeks once mature. Breeding occurs readily in established tanks with adequate food and stable conditions; separate pregnant females into a breeding box or heavily planted area to protect fry from predation. Fry are relatively hardy and will eat crushed flakes and micro foods immediately.

Common Diseases

Fin Rot

Symptoms

Frayed, discolored, or deteriorating fins; lethargy and loss of appetite

Treatment

Improve water quality with frequent partial changes, maintain temperature at 26-28°C, and treat with aquarium salt (1 teaspoon per 5 gallons) or antibacterial medication if severe

Ich (Ichthyophthirius multifiliis)

Symptoms

White spots on body and fins, scratching against objects, rapid breathing

Treatment

Raise temperature gradually to 28-30°C, perform daily 25% water changes, and treat with ich medication or aquarium salt for 7-10 days

Velvet Disease

Symptoms

Fine golden or rust-colored dust on body, clamped fins, lethargy, rapid gill movement

Treatment

Increase aeration, raise temperature to 28°C, reduce lighting, and treat with copper-based medication or salt bath; isolate affected fish if possible

Dropsy

Symptoms

Swollen belly, scales standing out like a pinecone, lethargy, loss of appetite

Treatment

Isolate fish immediately, perform frequent water changes, maintain optimal water quality, and treat with antibacterial medication; prognosis is often poor

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Quick Facts

diet
Omnivore – flake, spirulina, vegetables, brine shrimp
lifespan
3–5 years
max size
12 cm (4.7 in) females; 8 cm (3.2 in) males
tank size
20 gallons minimum
temperament
Peaceful; males may harass females

Water it likes

ph
7.0–8.5
ammonia
0 ppm
nitrate
<20 ppm
hardness
10–25 dGH
temperature
75–82°F (24–28°C)

Stats

Community tips0
Kept by0 hobbyists